This invention relates to a portable exercise device; and, more particularly, it relates to a pneumatic vacuum isometric body exerciser for working various muscle groups. Recently, there has been a growing trend in the number of people using various types of portable exercisers. Portable exercisers frequently use resistance. The use of resistance in a workout has been found to rapidly tone and develop muscles, as well as provide cardiovascular benefits. Notwithstanding the benefits to be gained by the use of these resistance exercisers, there are several problems inherent in the use of pneumatic exercisers which operate on the principle of compressing and expanding gases. Examples of such exercisers can be found in U.S. Pat. Nos. 3,174,343, 3,471,145, 4,290,600, 4,333,645, 4,376,533, 4,772,016, 5,004,630, and 5,152,732.
One problem with these exercisers involves the variability of resistance during compression and expansion strokes. Some exercisers do not offer the ability to vary resistance during compression and expansion strokes of the exerciser, e.g. U.S. Pat. Nos. 4,290,600, and 4,376,533. Of the types of exercisers found in the art that offer variable resistance during compression and expansion strokes, resistance is regulated by adjusting the flow of air through a valve or internal bore, e.g. U.S. Pat. Nos. 3,174,343, 3,471,145, 4,333,645, 4,772,016, and 5,044,630. However, as the piston seals in these devices wear over time the resistance variability these devices offer decreases.
A secondary problem associated with devices in the art involves a lack of stability during expansion and compression strokes. These devices contain both a piston and a piston rod. However, the piston rods in these devices are not stabilized so as to allow for a smooth lateral stroke during expansion and compression strokes, e.g. U.S. Pat. Nos. 4,3321,645, 4,772,016, and 5,044,630.
It would be highly desirable to solve the plethora of problems faced in the art and it is an object of the present invention to solve these problems. The present invention targets the thousands of health conscious individuals who train annually in the United States and worldwide, and serves these markets by providing a pneumatic vacuum isometric body exerciser that allows for increased variability of resistance, and that allows for increased smoothness of use during expansion and compression strokes.